The Sanders campaign, which is funded primarily by small-dollar donors, paid Apollo Jets $297,685.50 on Oct. 10, FEC records reveal. The payment was marked for “transportation.”

“This expense was for transportation for the senator’s 9-day, 9-state tour to support Democratic candidates up and down the ballot ahead of Election Day,” campaign spokeswoman Arianna Jones told local website VtDigger.com, which first reported on the jet expenses.

“This cost covered the entirety of the tour from Indiana, Michigan, Wisconsin, Iowa, South Carolina, Colorado, Nevada, Arizona, California, and back to Vermont,” Jones said.

Sanders’s private jet use comes despite the senator’s hard-line stance on climate change, which he has consistently called “the single greatest threat facing our planet.”

“The campaign purchased carbon offsets from NativeEnergy to support renewable energy projects and invest in carbon reduction projects to balance out the emissions produced on the trip,” Jones told The Daily Caller News Foundation.

Carbon offsets in theory allow polluters to cancel out their emissions by funding projects aimed at reducing emissions.

The same day his campaign cut a check to the private jet company, Sanders called climate change a “planetary crisis.”